This invention relates to radio control equipment, and, more particularly, to an improved control stick assembly for radio control equipment.
A number of years ago, radio control equipment became available for the purpose of remotely controlling model vehicles, such as airplanes, boats, and automobiles. Since that time, radio control of model vehicles has grown into a very popular recreational activity, and has even become organized into competitive events and contests at the local, national, and international levels. Radio control equipment is also finding nonrecreational uses, such as the control of wheel chairs, materials handling equipment, and so forth.
A typical radio control system comprises a radio transmitter and a control stick assembly operated by a human attendant, and a radio receiver and a servo actuator located at a remote element to be controlled, such as an airplane elevator, an automobile steering wheel, or a boat rudder. As the human attendant moves the control stick, the transmitter generates a radio signal having a characteristic proportional to the displacement of the control stick. This radio signal is intercepted by the receiver and applied to the servo actuator to move the remote element by an amount proportional to the displacement of the control stick. Many radio control systems are equipped for multichannel operation, thus permitting simultaneous control to be exercised over several remote elements, e.g., elevation, aileron, and throttle.
Usually, the proportional characteristic is pulse duration. A potentiometer at the transmitter whose shaft is coupled to the control stick controls the pulse duration of the radio signal. Springs associated with the control stick assembly urge the control stick toward a stationary, neutral position. A trim lever is coupled to the potentiometer housing to permit control of the position of the remote element independent of the control stick displacement. Thus, a temporary change in position of the remote element introduced by the control stick can be maintained permanently by adjusting the trim lever until the control stick is located in the neutral position. This trim maneuver requires the simultaneous coordinated operation of the control stick and the trim lever, which is an awkward and difficult task, particularly in multichannel operation.